1. Field of the Invention
The present invention relates to a projector, and more particularly, to a cooling apparatus for projector.
2. Description of the Prior Art
With the benefit of the developed electro-optics technologies, a high power light source has been incorporated into a projector so as to project a more sharper and brighter image over the screen facilitating an excellent briefing and presentation results toward the viewers. However, high power light source generates high heat.
Even a cooling fan has been incorporated to dissipate the heat, the high power light source is too hot which increases the working temperature of the cooling fan noises will be heavily increased by increasing the rotational speed of the fan as well as putting more cooling fans into the system. It has become a tough issue to provide an efficient cooling effect while reduces the acoustic noises.
Please refer to FIG. 1, which is an optical system according to the prior art. The optical system comprises an illumination system 10 and an imaging system 20. The illumination system 10 includes a light source 11 emitting a light beam toward a lens array 12. The lens array 12 comprises a plurality of small lens which jointly to evenly distribute the brightness of the light beam. Finally, the light beam pass through an illumination lens set 13 to converge the light beam into the imaging system 20. The imaging system 20 separates the light beam into red light and other visible lights through a first dichroic mirror 21. The red light is reflected by the first dichroic mirror 21 and enters the first reflection mirror 211. The red light further enters a first lens set 212 consist of a retarder, a liquid crystal display and a polarizer. The red light then enters the X-prism 24, while the other visible lights transmit through the first dichroic mirror 21 and enters a second dichroic mirror 22. The other visible lights is separated into blue and green lights by the second dichroic mirror 22. The blue light is reflected by the second dichroic mirror 22 and enters a second lens set 221 consist of a retarder, a liquid crystal display and a polarizer. The green light passes through the second dichroic mirror 22, the third reflection mirror 222 and fourth reflection mirror 223, and enters a third lens set 224 consist of a retarder, a liquid crystal display and a polarizer. The red, green and blue lights is synthesized by the X-prism then penetrate through a projection lens 25 and project onto the screen (not shown).
As shown in FIG. 2, the illumination system 10 uses a lamp of high power. Except the light source 11 has to cool, the optical system components which is heated up by the light beam has to been cooled as well so as to prolong the lifespan otherwise the characteristics and lifespan of the optical system components will be deteriorated. In the conventional projector, a main fan 31 is disposed on a case 30 which is located behind the light source 11 so as to cool the components of the imaging system 20 and the illumination system 10. In addition, in order to prevent the circuitry system34 from being heated, a partition 35 has been incorporated to as to isolate the circuitry system 34 and the optical system. In addition, a circuitry fan 36 has been used to cool the circuitry system 34. In addition, in order to efficiently cool the burner 112 within the lamp case 111, an auxiliary fan 32 located at the partition 35 adjacent the light source 11 is used to draw the cooling air into the circuitry system 34, as shown by the arrow. The cooling air is then guided by a duct 33 toward the lamp case 111. As a result, the cooling air is guided from one front end of the inner of the lamp case 111 to cool the burner 112 and the radiant heat of the inner of the lamp case 111. The heated air is guided to the front end of the lamp case 111 and exhausted from the case 30 by the main fan 31.
However, in the conventional projector, the heated air from the optical system and the circuitry system 34 is exhausted only by the main fan 31. As such, the working temperature of the main fan 31 is increased tremendously thereby shorting its lifespan. Even the rotational speed of the fan can be increased, more fans can be put into the projector, cost and acoustic noises will inevitably increase as well. Furthermore, the controlling system will become more complicated and reducing the reliability and the quality.